ABOARD THE CNN ELECTION EXPRESS, Iowa (CNN) - Democrat Barack Obama sharply pushed back on rival Hillary Clinton's earlier suggestion that his campaign is politicizing the death of Benazir Bhutto, telling CNN it is the Clinton camp that is doing the politicizing.

"The Clinton campaign started pushing this notion, immediately after this happened, that somehow this was going to advantage their campaign, and one of my campaign aides responded," Obama told CNN's Jessica Yellin. "But I think what the American people are concerned about right now is not how it impacts the vote in Iowa, they're concerned how it's going to impact the long term national security of the United States of America, and that's what we have to stay focused on."

In a Clinton interview with CNN earlier Friday, she said recent comments from top Obama strategist David Axelrod that seemed to draw a line from her initial support of the Iraq war to Bhutto's death amounted to "politicizing this tragedy."

"I just regret that he would be politicizing this tragedy, and especially at a time when we do need to figure out a way forward," Clinton said in the interview.

Obama said he had never met Benazir Bhutto, and has not met Pakistan President Pevez Musharraf, but said his judgment in not supporting the U.S. invasion of Iraq was more important than prior international contacts.

"Ultimately, this isn't about who you met with, it's about the decisions you make about the American people," he said.

In the wide-ranging interview, Obama also took aim at John Edwards, suggesting his rival’s current campaign mantra of taking on Washington's special interests is at odds with his past. (Related: Obama, Edwards direct fire at each other)

"I just think you look at the track record. What John is talking about now is not what he was talking about four years ago," Obama said. "It is not what he was talking about eight years ago."

"On issue after issue he now says he made a mistake," he added. "But when he suggests he's somehow going to fight on behalf of the American people then, I have to point out my track record of fighting on behalf of working families has been unwavering."

(CNN) - Just hours after Mitt Romney’s campaign debuted a new New Hampshire television ad criticizing John McCain, the Arizona senator’s campaign shot back with a spot that took aim at Romney – its first ad to mention an opponent by name.

“As you hear Mitt Romney attack John McCain, consider these words from New Hampshire newspapers,” says the announcer. “The Union Leader says John McCain has ‘conviction’ and Granite Staters want a candidate who will look them in the eye and tell them the truth. John McCain has done that. Mitt Romney has not."

The 30-second spot will begin airing this evening in New Hampshire, where McCain is now a close second to the former Massachusetts governor in most recent polls.

A McCain campaign official tells CNN the "counterpunch" has been ready for several days, in anticipation of a Romney TV attack in the Granite State.

UPDATE: Romney spokesman Kevin Madden responded within minutes of the ad's release. "Sen. McCain has a troubling history of neglecting substantive issues and getting personal in his attacks against those who happen to disagree with him. It’s the McCain way," he said.

DES MOINES, Iowa (CNN) - A senior official on Republican Mike Huckabee’s campaign told CNN Friday that staffers are aware of the problem posed by the fact that their candidate has “no foreign policy credential,” and that unlike many other presidential candidates, he can’t boast about having known Benazir Bhutto.

The Huckabee official said he told the former Arkansas governor that reaction to the crisis in Pakistan will be the story for the next several days, and that until they “get him briefed and up to speed” on Pakistan, a good place for Huckabee to draw the line is on illegal immigration.

“Why does Rudy Giuliani get more credentials on homeland security than you do? You’ve been a governor,” the Huckabee campaign official said he told the candidate.

The campaign official admitted that Huckabee’s tough talk on on immigration is also aimed at helping him with male Iowa GOP voters - a voting bloc the official concedes they have been losing ground with.

CORALVILLE, Iowa (CNN) -Barack Obama pushed back hard against his Democratic rivals Friday, telling an overflow audience that Hillary Clinton and John Edwards don't have the right credentials to bring about change, the buzzword that’s come to dominate the Democratic dialogue leading up to next week's Iowa caucuses.

Obama, who is in a dead heat with Clinton and Edwards in most recent Iowa polls, first took aim at the New York senator's claim that he lacks foreign policy experience, dismissing a recent criticism from former President Bill Clinton that a vote for Obama would be a "roll of the dice."

The Illinois senator said the same criticisms came out of the Washington establishment when Clinton himself ran for president in 1992.

"My experience is grounded in understanding how the world sees America, from living overseas and traveling overseas, and having family beyond our shores," Obama said. "It's that experience, that understanding, and not just of what world leader I went and talked to in the ambassador's house who I had tea with."

Obama then pivoted to Edwards, who gave a speech on "Change" in Dubuque today in which he said that special interests won't "give up their power because we ask them nicely," a jab that seemed to be aimed squarely at Obama.

Obama urged the crowd to look at a candidate's "track record" in fighting against special interests and suggested Edwards' lucrative former career as a trial lawyer contradicts his current populist overtures.

(CNN) - Republican presidential candidate Mike Huckabee's understanding of foreign affairs has again been called into question after his comments reacting to the assassination of former Pakistani Prime Minister Benazir Bhutto.

Huckabee, whose foreign policy credentials have been under a microscope since he admitted that he was unaware of an intelligence report that Iran had suspended its nuclear weapons program, appeared to make another gaffe Thursday when he seemed to suggest incorrectly that Pakistan was under martial law.

At an Orlando, Florida, press conference, the former Arkansas governor told reporters that the United States' first priority should be to find the responsible parties.

CNN Contributor David Gergen says Edwards is the one to watch in Iowa.

From CNN Contributor David Gergen

The assassination of Benazir Bhutto, potentially leading Pakistan to the brink of a civil war, would seemingly give a last-minute lift to candidates with experience in national security, especially Hillary Clinton and John McCain and, yes, Joe Biden.

But Iowa may have its own dynamic heading toward the caucuses - a good reason to keep your eye on John Edwards as he appears on AC 360 tonight.

In the final days before the Iowa caucuses, Obama and Edwards are turning up the heat on each other. (Photo credit: Getty Images)

WASHINGTON (CNN) - With less than a week before Iowa voters kick off the presidential primary season, Democrats Barack Obama and John Edwards - who had until recently directed most of their criticism towards Hillary Clinton - continued taking jabs at one another Friday, each trying to portray the other as an insufficient agent of change against Washington’s special interests.

Edwards' latest veiled shot at Obama is expected to come in an Iowa speech later Friday, when he will not-so-subtly challenge Obama for taking money from lobbyists in the past. (Obama has not taken any money from lobbyists for his presidential campaign, but has accepted money from them for past campaigns. Edwards maintains he has never accepted money from lobbyists or Political Action Committees.)

"Nobody who takes their money and defends the broken system is going to bring change," Edwards will say, according to prepared remarks. "And, unfortunately, nobody who thinks we can just sit down and talk them into compromise is going to bring change either."

Obama often says he has ability to bring people together and forge compromises.

The comment follows a more pointed one from Obama late last week, when he hit Edwards for not using his influence to end the actions of third-party groups that support his presidential campaign and have been attacking both Obama and Clinton.

"You can't say yesterday you don't believe in it, and today three-quarters of a million dollars is being spent for you," said Obama. "You can't just talk the talk. Everybody talks change, but how did they act when it was not convenient, when it's hard?"

Obama continued hitting that theme in his revamped stump speech Thursday, saying, "I don’t need any lectures on how to bring about change, because I haven’t just talked about it on the campaign trail. I’ve fought for change all my life."

Obama's campaign also released a 'fact check' Friday morning designed to portray Edwards as a onetime friend of interest groups, and a letter from eight former Edwards supporters who say they have switched their allegiance to Obama because of the former North Carolina senator's refusal to renounce the third-party ads.

"He said he would change Washington, and we believed him," the letter says. "Times have changed, and so has John Edwards."

The latest back and forth comes as several recent polls show the three candidates continue to be deadlocked in the Hawkeye State.

"I just regret that [Obama and his chief strategist] would be politicizing this tragedy, and especially at a time when we do need to figure out a way forward," Clinton said Friday in an interview with CNN's Wolf Blitzer.

Her comments followed criticism from Obama's campaign implying that some of Clinton's foreign policy decisions raise questions about whether she should be president.

Martin Sheen, AKA former President Josiah Bartlet, is hitting the trail with Richardson.

WASHINGTON (CNN) - Hillary Clinton isn't the only White House hopeful to barnstorm Iowa with a former president this year.

Former TV President Josiah Bartlet, also known as actor Martin Sheen, is set to hit the trail with Bill Richardson this weekend. Sheen announced his support for Richardson earlier this month, hailing the New Mexico governor as "ready for prime time."

Sheen is no stranger to the White House - at least, not the Hollywood version. He has played the President of the United States at least four times: in addition to his run on The West Wing, Sheen played the commander-in-chief in the 1983 mini-series Kennedy, the 1987 TV movie Medusa's Child, and the 1983 movie The Dead Zone.

"I am looking forward to Martin showing me around the White House, and I hope I can serve as many terms in the White House as his characters have," said Richardson.

But it's unclear whether Sheen's endorsement will pay off at the polls. In 2004, when he was a TV "sitting president," Sheen campaigned for Howard Dean - the onetime Democratic frontrunner whose campaign quickly fizzled when the primary season began.

UPDATE: More than one member of the Bartlet administration is set to campaign in Iowa this weekend. Richard Schiff, Bartlet's hardened Communications Director Toby Ziegler on the show, will campaign with Democrat Joe Biden, the Delaware senator's campaign announced.

“The West Wing inspired its audience to seek the kind of presidential leadership that is based on experience, judgment, wisdom, and conscience,” Schiff said.

"Iowa, and America, need Joe Biden because he is ready to lead from Day One and in the high-stakes world we live in, there are no re-takes.”

WASHINGTON (CNN) - He's no Ron Paul, but John McCain is benefiting from a mini-surge in Internet fundraising of late.

A campaign source familiar with the numbers say the McCain campaign raised "just under" $1 million in Internet contributions over the past two weeks.

Hardly a match for the eye-popping Internet fund-raisers organized by the Paul campaign. But it is nonetheless a development helping morale in the McCain camp - after a dismal summer slide in the polls and fundraising, a recent up tick, especially in New Hampshire is, as the source put it, "helping the bottom line at a time every dollar counts."